Belt grinding and polishing machine



Dec. 18, 1951 s. BADER 2,578,662

BELT GRINDING AND POLISHING MACHINE Filed July 2a, 1948 2 SHEETS-SHEET l 5; l K ---35 Q R23 INVENTORQ 5 2f ephen Bader BY v Dec. 18, 1951 s BADER 2,578,662

BELT GRINDING AND POLISHING MACHINE Filed July 28, 1948 2 SHEETSSHEET 2 Step/2 en Bade! Y Patented Dec. 18, 1951 UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to a surface grinding machine of the abrasive endless belt type.

In grinding machines of this general character the abrasive belt is itself, in its unsupported areas, used for grinding and finishing purposes. The rollers which support it serve either primarily or exclusively as pulleys and they do not participate directly in the grindin or finishing operation. This is especially true of those grinding machines which are designed for use on concave and convex surfaces and irregular surfaces generally. The abrasive belt is sufficiently flexible, intermediate the rollers which support it, to conform to the contours of the work. The rollers are rigid in construction and unyielding and hence the abrasive belt which they support is itself rendered inflexible in the areas which are in direct, although passing contact therewith. When it is desired to grind or polish regular or fiat surfaces, the work may be held against those areas of the abrasive belt which are directly supported by the rollers.

It is a principal object of this invention to provide a grinding machine of the type which is adapted to engage uneven or irregular surfaces, not only intermediate the rollers which support the belt but also in the roller supported areas. In this machine the unsupported belt areas may be utilized for grinding and polishing purposes.

But so may the supported belt areas for the reason that the supporting rollers (or one of them) are provided with yielding bearing surfaces which yieldingly support the belt and thereby enable the belt to retain its flexibility even while it is in direct contact with the rollers. There is a decided advantage in utilizing the roller supported belt areas for the finishing or grinding operations, as distinguished from the unsupported belt areas which lie intermediate the supporting rollers. The advantage is simply this: that a more forceful contact between the work and the abrasive belt may be had in the supported areas of the belt than in its unsupported areas, with a consequent lessening in the likelihood that the belt will break.

It is accordingly a corollary object of this invention to provide a belt supporting roller in a machine of this general character, which is equipped with a relatively soft or yielding bearing surface. The use of a roller of this kind insures uninterrupted flexibility in all of the operative or contact areas of the belt, including those areas which are in momentary, direct contact with the roller.

Another object of this invention is the provision of a polishing and grinding machine of the character described wherein the belt supporting rollers are themselves adequately and properly supported. Reference is here made especially to that roller against which the work is made to bear. This roller is supported on both sides rather than only on one. In other grinding machines the supporting pulleys are supported on one side only to render them easily accessible for removal and replacement purposes. Although the work-engaging roller in the present machine is supported on both sides, it is nonetheless equally accessible for the same purposes.

A further object of this invention is the provision of a polishing and grinding machine of the character described in which the work-engaging roller is adjustably mounted to enable it to support the endless belt in proper alignment and at a selected height above the floor on which the machine stands.

A preferred form of this invention is shown in the accompanying drawing in which:

Fig. 1 is a side view of a polishing and grinding machine incorporating the features of this invention;

Fig. 2 is an enlarged similar view of the back of the machine;

Fig. 3 is a back view thereof;

Fig. 4 is a detailed sectional view of the front or work-engaging roller, the roller shown having a relatively small outer diameter;

Fig. 5 is a fragmentary view, similar in section to that of Fig. 4, of another front or work-engaging roller, this roller being of a relatively large outer diameter; v

Fig. 6 is a front view of said last mentioned roller, showing how it supports a relatively wide, flexible abrasive belt;

Fig. '7 is a top view of said roller and of its adjustably mounted support; and

Fig. 8 is a side view, partly in section, of said roller and said support.

The polishing and grinding machine herein claimed is provided with two spaced stands or bases: a forward or front base Ill and a rear base II. A framework which includes two uprights I? and i3 respectively, a cross-piece l4 aflixed to the top of the two uprights and a crosspiece l5 which is affixed to the two uprights intermediate their top and bottom ends, is mounted on rear base II. Another upright or post i6 is mounted on base l0. These two bases and the structures which they support constitute the framework of the present machine. It will be noted that the front base and the structure which it supports are completely separate and independent in respect to the rear base and the structure which it supports. Hence it is possible to space the two bases in accordance with individual requirements and preferences. By the same token the two bases may be placed on irregularly surfaced floors or even on different levels.

An electric motor M drives the machine and it will be seen in Fig. 3 that this motor is mounted on the rear base II. The motor-shaft extends between the two uprights l2 and I3 and it supports or carries a pulley 2|. This pulley is one of three on which the endless abrasive belt 22 is mounted. A second pulley 23 is mounted on a shaft 24 which is affixed to a block 25 slidably mounted on uprights l2 and I3. Block or slide 25 is movable in either direction, vertically of the uprights and hence pulley 23 is also movable in either vertical direction.

It will be noted in Fig. 2 that cross members 14 and I5 support a screw which is disposed in parallel relation to uprights l2 and I3. A hearing 3| is provided on cross member l5 to support the bottom end of the screw and the upper end of said screw extends through a hole 32 in the upper cross member l4, in which it is journaled. Collars 33 and 34 respectively are aflixed to the screw on the two sides of cross member l4. These collars prevent longitudinal or vertical movement of the screw relative to the cross members and hence relative to the rear framework as a whole. The screw is free however, to engage in rotary movement in hole 32 and bearing 3!. Screw 30 extends through a tapped hole 35 in slide 25. The screw threads of screw 30 are in engagement with the screw threads of the tapped hole and hence vertical movement of slide 25 may be caused by simply rotating the screw, the direction of movement of the slide being determined by the direction of rotation of the screw.

It is by the screw means last above described that the position of pulley 23 relative to pulley 2| may be changed. The two pulleys may be spaced nearer to or farther from each other, depending upon individual requirements. Although this feature appears to comprise an unimportant adjustment facility, actually it has great importance and it performs a number of functions, among which the following may be listed: This adjustment feature renders it possible for the machine to accommodate endless belts of varying lengths, irrespective of the fact that the two bases of the machine may be fixedly positioned relative to each other. This feature also renders it possible to loosen or tighten the belt for more efficient operation thereof or to facilitate removal of the belt and replacement thereof by another belt. Furthermore this feature cooperates with other constructional features of the machine to enable the abrasive belt to be maintained at a higher or lower operational level, thereby enabling the operator of the machine to assume either a standing or sitting position relative thereto.

The two pulleys 2| and 23 above described may be of purely conventional construction as may the abrasive belt 22. The dimensions of the pulleys and the belt may be made to conform to the specifications of the industry. The third pulley shown in Figs. 5 and 6 is however, unique in its construction. This pulley includes a hub 4i and a pair of bearings 42 which support the hub on a shaft 43. It will be seen in Fig. 5 that hub M is externally threaded to receive a pair of internally threaded retaining rings 44. There are two such rings on the single hub, one at each end thereof, and sandwiched in between said retaining rings is a relatively soft cushion 45. This cushion may be unitary in structure or it may comprise a plurality of cushions held side to side by the retaining rings. Cushion 45 is, of course, of annular shape so that it may be mounted on the hub between the two retaining rings. The outer diameter of the cushion exceeds the outer diameter of the two retaining rings so that it will be apparent that the peripheral or marginal portions of the cushion remain unsupported by the retaining rings. It is this relatively flexible cushion that directly engages and supports the abrasive belt. The cushion need not be as wide as the belt as witness Fig. 6. The tendency of the belt to curve transversely of itsell, whether of its own volition, or by reason of its contact with a piece of work having a curved surface, communicates itself to the flexible cushion and impresses a corresponding curvature therein. Again see Fig. 6. This ability of the belt to curve transversely of itself is rendered possible solely by reason of the inherent flexibility of the cushion which supports it. If this cushion were wholly inflexible as is the bearing surface of conventional pulleys, the tendency of the belt to curl would very positively be arrested, reference being made of course, solely to that portion of the belt which happens to be in direct contact with the bearing surface of the pulley.

This third pulley '40 which is the front pulley of the machine constitutes what may be called the work-engaging pulley although strictly speaking the abrasive belt is always interposed between the work and the pulley, and the work is never in direct contact with the pulley itself. Since the cushioned bearing surface of this workengaging pulley or roller is adaptable to varying contours it may be used in connection with work having concave or convex surfaces or surfaces which are in other respects irregular.

Work-engaging roller 40 has a relatively large outer diameter. Work-engaging pulley 50, shown in Fig. 4, has a, relatively small external diameter. Like pulley 40 it has a hub 5| which is supported by means of bearings 52 on shaft 53. Hub 5| may be externally threaded to receive internally threaded retaining rings 54. The cushion of roller 50 comprises a plurality of annular cushions 55 mounted on said hub between the two retainings rings thereof, and spaced from each other by means of spacing rings 56. The peripheral portion of said cushions 55 extends beyond the peripheral portions of retaining rings 54 and spacers 56.

Seals 51 are afllxed to bearings 52 to prevent foreign matter from entering the bearings. It will be noted that an annular space 58 is provided between the shaft and the hub and it will be understood that a lubricant may be introduced into this space to keep the bearings adequately lubricated at all times. Seals 51 will prevent the lubricant from escaping. This same lubricating feature may be incorporated into roller 40.

It will be noted in Fig. 4 that shaft 53 has reduced portions '53 at the extremities thereof, as is shown in dotted outline, thereby providing a pair of annular shoulders against which the bearings 52 abut to prevent the same from displacing toward each other. In order to prevent displacement of the bearings away from each other, sleeves such as 53" are disposed about the reduced extremities 53' of the shaft. It will be understood that the shaft and sleeve construction thus described is equally applicable to roller 40 shown in Fig. 5.

It will be seen in Figs. 7 and 8 that the shaft 43 of roller 40 is supported by means of a pair of spaced arms 60 and 6| respectively which are connected to or integral with a plate 62. It will be noted that notches are formed in arms 6|] and 6| to accommodate and position shaft 43. These notches are best shown in Fig. 8 and are indicated therein by means of the reference character 69. They are of bayonet slot shape in order to hold the shaft securely. The shaft and its roller may however, very readily be removed from their supporting arms 60 and 6| by simply raising the shaft out of its notch-shaped seats.

Plate 62 is pivotally mounted on block 63 by means of pin or bolt 64. This plate is provided with a curved slot 65 which accommodates another pin or bolt 66. Both pins or bolts are fastened to block 63. It will be evident from the foregoing that plate 62 is free to pivot around bolt 64 to the extent permitted by slot 65. A nut 61 may be applied to bolt 66 to tightly engage plate 62 and prevent pivotal movement thereof.

The pivotal construction last described may be used to align roller 40 with rollers 2| and 23. For precision adjustment of plate 62 about its pivot 64 an adjusting screw 10 is provided. This adjusting screw is pivotally connected to the plate at II, and it is engaged by an internally threaded sleeve 12. This sleeve is also pivotally mounted, but its pivotal connection indicated by means of the reference character 13 is with block 63 rather than with plate 62. This sleeve is provided with a knob M by which it may be rotated in either direction. Screw 10 and sleeve 12 function in the manner of a turn-buckle between plate 62 and block 63. It is thus possible by rotating knob M in either direction to cause a pivotal movement of plate 62 and hence of roller relative to block 63.

Block 63 is pivotally mounted on post M5 by means of pin or bolt 8|]. Bolt 8|] extends on a horizontal line and parallel to it is a second bolt 8|. These two bolts are aflixed to block 63, bolt 89 extending through a hole in post l6 and bolt 8| extending through a curved slot 82 in said post. Block '63 and hence plate 62, arms 60 and SI and roller 40 are therebyenabled to pivot on a horizontal pivot to the extent limited by slot 82. Bolt 8| may be tightened against post Hi to securely position block 63 in any angular position in which it is desired to place the block. Roller 46 may thereby be raised or lowered to any desired position. Handle 90 on screw 30 may be used to rotate said screw and thereby to raise or lower roller 23.

The foregoing is descriptive of a preferred form of this invention and it will be appreciated that this form may be modified in different ways, and other forms may be provided, within the broad scope of this invention. The cushioned work-engaging roller may for example, be used in conjunction with other types of polishing and grinding machines. The cushion itself may be made of many different materials, such as, cloth, soft rubber, felt, sheepskin, hair or wire. The cushion may be made in varying degrees of flexibilit or softness.

I claim:

1. A machine of the character described, comprising a pair of spaced frames, a pair of rollers rotatably mounted on one of said frames, 3, third roller mounted on the other of said frames, an endless abrasive belt mounted on all three rollers, one of. the two rollers on the first mentioned frame being connected to a power drive to cause rotation thereof and lengthwise movement of the belt, the other of said two rollers being adjustably positioned on said first mentioned frame relative to said power driven roller, the third roller being provided with a cushioned bearing surface for the belt to enable the belt, while in contact with said roller, to conform to the contours of irregular work surfaces, said cushioned roller being adjustably mounted on said second mentioned frame to enable it to be raised or lowered to any desired position, said cushioned roller being also swivelly mounted on said second mentioned frame for sidewise movement about a substantially vertical axis intermediate the axis of said third roller and a plane passing through the axes of said pair of rollers, whereby said cushioned roller may be aligned with the other two rollers.

2. A machine of the character described, comprising a pair of spaced frames, one of said frames having a notched support facing with the open end of said notch away from the other of said frames, a pair of rollers rotatably mounted on one of said frames, a contact roller, means for rotatably mounting said contact roller in said notch, said support being mounted on pivot means intermediate the axis of said contact roller and a plane passing through the axes of said pair of rollers and said pivot means being pivotal about two mutually perpendicular axes, one of said pair of axes being substantially perpendicular to the axis of said contact roller an endless abrasive belt extending about all three of said rollers, one of the two rollers on the first mentioned frame being connected to a power drive to cause rotation thereof and corresponding lengthwise movement of said belt, at a constant speed, irrespective of the diameter of said contact roller, the other of said two rollers on said first mentioned frame, being adjustably positioned relative to said power driven roller, to compensate for changes in diameter of the contact roller, said contact roller being provided with a cushioned bearing surface for the belt to enable the belt while in contact therewith, to conform to the contours of irregular work surfaces.

3. A machine of the character described, comprising a pair of spaced frames, one of said frames having a notched support facing with the open end of said notch away from the other of said frames, apair of rollers rotatably mounted on one of said frames, a contact roller, means for rotatably mounting said contact roller in said notch, said support being mounted on pivot means intermediate the axis of said contact roller and a plane passing through the axes of said pair of rollers and said pivot means being pivotal about two mutually perpendicular axes, one

of said pair of axes being substantially perpendicular to the axis of said contact roller an endless abrasive belt extending about all three of said rollers, one of the two rollers on the first mentioned frame being connected to a power drive to cause rotation thereof and lengthwise travel of said belt, the other of said two rollers on said firstmentioned frame being adiustably positioned relative to said power driven roller, said contact roller being provided with a cushioned bearing surface for the belt, to enable the belt while in contact therewith, to conform to the" contours of irregular work surfaces, and said cohtact roller being driven only by said belt, where by said contact roller may be readily removed upon removal of the belt.

4. A machine of the character described comprising, a pair of spaced frames, a pair of rollers mounted on one of said frames, a third roller mounted on the other of said frames, and an abrasive belt extending about all three of said rollers, one of said rollers being a work-engaging roller having a resilient bearing surface whereby the belt and work-engaging roller may yield to accommodate surfaces of irregular contour, said work-engaging roller further being adjustable about vertical and horizontal axes with respect to the remaining rollers, said vertical axis being intermediate the axis of said third roller and a plane passing through the axes of said pair of rollers, one of said pair of rollers being adjustable vertically with respect to the remaining rollers and the other of said pair of rollers being connected to a power drive for imparting rotary motion thereto.

5. A polishing and grinding machine comprising a pair of rollers, means rotatably mounting said rollers with the axis of one roller spaced from the axis of the other roller, a third roller, means rotatably mounting said third roller with its axis spaced from the axes of said pair of rollers, and an endless abrasive belt mounted on all three of said rollers, said third roller having a relatively soft, cushioned bearing surface for said belt to enable the belt, while in contact with said third roller, to conform to the contours of irregular work surfaces and said mounting means for said third roller including means for adjusting said third roller in a direction perpendicular to an axis intermediate the axis of said third roller and a plane passing through the axes of said pair of rollers, said intermediate axis also being substantially perpendicular to a plane passing through the axis of said third roller.

6. A polishing and grinding machine comprising a pair of rollers, means rotatably mounting said rollers with the axis of one roller spaced from the axis of the other roller, a contact roller, means rotatably mounting said contact roller with its axis spaced from the axes of said pair of rollers and with its axis on a line perpendicular to and intersecting a line between the axes of said pair of rollers, and an endless abrasive belt mounted on all three of said rollers, said contact roller having a relatively soft, cushioned bearing surface for said belt to enable the belt, while in contact with said contact roller, to conform to the contours of irregular work surfaces and said mounting means for said contact roller including means for adjusting said contact roller in a direction perpendicular to an axis intermediate the axis of said contact roller and a plane passing through the axes of said pair of rollers, said intermediate axis also being substantially perpendicular to a plane passing through said axis of said contact roller.

7. A polishing and grinding machine comprising a pair of rollers, means rotatably mounting said rollers with the axis of one roller spaced from the axis of the other roller, means for driving one of said rollers, a contact roller having a relatively soft, cushioned outside surface, means rotatably mountin said contact roller with its axis spaced from the axes of said other rollers, said mounting means for said contact roller including means for rotating said contact roller about an axis substantially perpendicular to a plane passing through said axis of said contact roller and intermediate said axis of said contact roller and a plane passing through said axes of said pair of rollers, and an endless abrasive belt mounted on all three of said rollers.

8. An endless abrasive belt polishing and grinding machine comprising in combination a, pair of rollers, means for rotatably mounting said rollers upon their central shafts with the shaft of one roller spaced from the shaft of the other roller, a third roller comprising a contact roller having a relatively soft, cushioned outside surface to support an endless abrasive belt against the counterforce of an engaging work piece, means for rotatably mounting said contact roller with the central shaft thereof spaced from the shafts of said pair of rollers and with the planes of rotation of said rollers substantially coincident so that an endless abrasive belt may be mounted on all of said rollers for lengthwise movement thereon, said contact roller mounting means including means for rotating said roller about an axis substantially perpendicular to a plane passing through said contact roller shaft and intermediate the shaft of said contact roller and a plane passing through the shafts of said pair of rollers.

9. An endless abrasive belt polishing and grinding machine comprising in combination a pair of rollers, means for rotatably mounting said rollers upon their central shafts with the shaft of one roller spaced from the shaft of the other roller, means for moving one of said rollers relative to the other, a third roller comprising a contact roller providing a relatively soft, cushioned bearing surface for an abrasive belt to support the belt against the counterforce of an engaging work piece in a contour conforming to the work piece surface, means for rotatably mounting said contact roller as an idler roller with the central shaft thereof spaced from the shafts of said pair of rollers and with the planes of rotation of said rollers substantially coincident so that an endless abrasive belt may be mounted on all of said rollers for lengthwise movement thereon, said contact roller mounting means including swivel means to allow sidewise movement of said contact roller about a substantially vertical axis intermediate said contact roller and a plane passsaid pair of rollers,

STEPHEN BADER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

